As a cause of dental caries and periodontitis, adherence of the plaque (dental plaque) is known, and it has been pointed out so far that its removal and prevention of the adherence, namely plaque control is important in oral hygiene. Mechanism of the plaque formation is as follows; glucosyltransferase which is an extracellular enzyme of an intraoral microorganism, particularly, Streptococcus mutans synthesizes sticky and insoluble glucan, using sucrose as the substrate and the glucan attaches to tooth plane to form plaque which is bacterial aggregate.
As methods of plaque control, mechanical plaque removal with the toothbrush etc. and intraoral bactericide with bactericidal agents are general. However, the mechanical methods by such as toothbrush cannot remove the plaque fully unless performed for long time with skilled brushing technique requiring training.
On the other hand, bactericidal effect by bactericidal agents also has limitation. There is a problem that the effect cannot be exerted fully to the bacterial aggregate, because the bactericidal agent does not penetrate to its inside. Therefore, devising is required such as increasing of concentration of bactericides and making the processing time longer. Additionally, plaque removal by bactericides was not always satisfactory in terms of safety, economy and efficacy since they effect on all bacteria in the oral cavity resulting in killing bacteria oral indigenous and bacteria useful to human body.
Dentifrices and the like combining lactic acid bacteria or fermentation liquid of lactic acid bacteria have been proposed as oral cavity compositions containing bactericidal ingredients gentle to the human body, for example, in JP 2002-234825A and JP 2002-193777A. This condition can be explained as follows: when the dentifrices and the like effect in the oral cavity where offending bacteria of dental caries and periodontal disease exist, the offending bacteria of dental caries and periodontal disease fall into bacteriostasis that is caused by struggle for survival between bacteria each other. However, it has not always been satisfactory.
In view of conventional arts for plaque control using lactic acid bacteria as described above, there has been a demand for development of oral cavity preparations combining lactic acid bacteria which have properties such as inhibiting plaque formation by inhibiting Streptococcus mutans effectively which is a major cause of plaque formation as well as ability of inhibiting generation of bad breath.